Main frame of chairs



FIG. 1 is the front elevational view of main frame of chairs;

FIG. 2 is the rear elevational view thereof;

FIG. 3 is the right side elevational view thereof;

FIG. 4 is the left side elevational view thereof;

FIG. 5 is the top plan view thereof;

FIG. 6 is the bottom plan view thereof; and,

FIG. 7 is the main view thereof. 

The ornamental design for main frame of chairs, as shown and described. 